The invention relates to a, preferably bistable, electromagnetic actuator device, preferably comprising permanent magnet means, having a stationary spool unit, which can be energized, as well as an armature unit, which is movably guided along a displacement axis and which is movable with respect to the spool unit in reaction to the spool unit being energized, said armature unit consisting of one or several parts being able to be displaced between a parked position (preferably a first or rather inner stable position) and an actuating position (preferably a second or rather extracted stable position) in an output drive direction along a displacement axis in order to interact with an actuating element, which can in particular be a camshaft preferably comprising a displacement groove and which is disposed on an output side of the armature device, as well as being able to be rotated about the displacement axis, and spring means, which are supported against an abutment component preferably disposed in a torque-proof manner, being allocated to said armature unit in such a manner that said spring means apply a spring force to the armature unit in the output drive direction during the displacing movement while simultaneously partially relaxing and preferably apply a spring force to the armature unit when in the actuating position as well. Furthermore, the invention relates to a system which comprises an actuating element along with an electromagnetic actuator device, said actuating element applying a force, which rotates the armature unit about the displacement axis, to the armature unit when in its actuating position, which is in particular extracted from an actuator casing.
Electromagnetic actuating devices have long been known as actuators, in particular for a cam phasing unit or similar aggregates of a combustion engine, from the state of the art. Accordingly, the applicant's German patent DE 102 40 774, for example, discloses such a technology in which an armature unit comprising permanent magnet means forms a tappet or a tappet unit at its end in order to interact with an actuating element (such as an actuating groove of a cam shaft) and can be moved with respect to a stationary spool unit in reaction to the spool unit being energized. In practice, a repulsive magnetic field in reaction to the energizations is generated in such devices which removes the armature unit from a core from a parked position and drives the same to an engaging position (actuating position) with the actuating element in an output drive direction. Such devices, which are presumed to be known, are optimized not only electromagnetically and in regard of their dynamic behavior (development of force and speed) but are also particularly suitable in a proper manner for a large-scale production. The electromagnetic actuator device described in DE 102 40 774 can also be realized so as to be supported by a spring force in such a manner that the spring force supports the movement of the armature unit to the engaging position, the spring means required therefor being supported against the armature unit.
An alternative electromagnetic actuator device has been described in the applicant's patent DE 10 2012 107 922 A1, the armature unit of which also comprises a tappet or a tappet unit, respectively, at its end for interacting with an actuating element, in particular an actuating groove of a camshaft. In contrast to the technology described in DE 102 40 774, the armature unit does not comprise any permanent magnet means; like the spool unit, these permanent magnet means are disposed stationary and with respect to the spool unit in such a matter that the permanent magnetic flux is repelled from a section of the armature unit free of permanent magnets when energizing the spool unit so that this spring actuated by spring means is moved to an engaging position with the actuating partner in an output drive direction.
The two previously described embodiments of electromagnetic actuating devices for phasing a camshaft of a combustion engine have in common that the armature unit forms an actuating member of a cam phasing mechanism and engages in the groove of a camshaft when in its actuating position. Hence, the problem arises that the armature unit abuts against the flank of a groove during the process of axially displacing the camshaft and rolls off of there due to the rotational movement of the camshaft, whereby the armature unit first rotates in the one and then the other direction about its axial displacement axis during the process of displacing the camshaft. In a previously described actuator concept, which comprises spring means, which are supported against the armature unit on the one end and against a stationary abutment component on the other end and simultaneously exert a spring force on the rotating armature unit, this inevitably leads to an abrasion between the components rubbing against each other. In a worst case scenario, this effect can also lead to the spring means and the armature unit becoming wedged when the armature unit rotates against a winding direction of the spring means realized as, for example, a helical compression spring with the result that the spring means are unwound. Since only a comparatively low inherent rigidity of the spring leads to the desired displacement behavior of the armature unit in the previously described types of actuators, only springs having comparatively thin wire thickness, which are particularly susceptible to being unwound as previously described, can thus far be used with the given spatial construction requirements.